Testing retry logic without status_forcelist doesn't trigger a retry.

[joel-hall]

Describe the bug

I want requests to retry for connection errors, but responses seems to override the adapter send function and doesn't retry in that case. Is there an easy way to test only for exception cases?

Additional context

No response

Version of responses

0.25.7

Steps to Reproduce

import responses
from requests import Session
from requests.adapters import HTTPAdapter
from requests.exceptions import ConnectTimeout
from responses.registries import OrderedRegistry
from urllib3.util import Retry


@responses.activate(registry=OrderedRegistry)
def test_example():
    session = Session()
    # Note, no status_forcelist set
    retry = Retry(total=3, allowed_methods={"POST"})
    session.mount("http://", HTTPAdapter(max_retries=retry))
    url = "http://example.com/api"
    # This won't retry, doesn't honor Retry-After
    responses.post(url, body="Error", status=503, headers={"Retry-After": "1"})
    # This won't retry, it raises the exception though
    responses.post(url, body=ConnectTimeout())
    # This is never matched
    responses.post(url, body='{"message": "It worked."}', status=200)
    response = session.post(url, data={"key": "value"})
    # This assertion fails, status_code is 503
    assert response.status_code == 200

Expected Result

I expected responses to have a way to test retries from exceptions since it has the nice retry testing feature, but I didn't expect that status_forcelist was required. I actually consider this a feature expansion, but I was asked to open it as a bug.

Actual Result

For exceptions, responses doesn't retry. For statuses, it looks like it doesn't check for Retry-After header, only status_forcelist due to how urllib3 works. Personally, I'm interested in the exception case, and didn't look much at the Retry-After case.